This invention relates to inorganic fillers. More specifically, it relates to a method of reducing the binder demand of such fillers.
Certain particulate inorganic material such as ground limestone and talc are commonly employed as fillers in many industrial products. For example, those products based on thermosetting and thermoplastic resin formulations normally contain considerable amounts of filler. Particularly in the case of thermosetting resins, use of a filler not only reduces product cost but may also offer other advantages such as improvement in the molding characteristics of the formulation. Because of such advantages, the desire to incorporate the maximum amount of filler into these resins can readily be appreciated. Consequently, methods of reducing a filler's binder demand, which is generally considered as the amount of binder required to completely wet out the filler to produce a binder-filler mixture of a given viscosity, are constantly being sought.
Past attempts at reducing the binder demand of inorganic fillers have included such approaches as alteration of the particle size distribution of the filler to minimize its void volume, compaction techniques and surface coating of the filler. While each of these attempts has met with some success, a more satisfactory method is still desired. The primary objective of this invention therefore is to provide such a method.